rtems: Fix rate monotonic statistics

The rate monotonic period statistics were affected by
rtems_cpu_usage_reset().  The logic to detect and work around a CPU
usage reset was broken.

The Thread_Contol::cpu_time_used is changed to contain the processor
time used throughout the entire lifetime of the thread.  The new member
Thread_Contol::cpu_time_used_at_last_reset is added to contain the
processor time used at the time of the last reset through
rtems_cpu_usage_reset().  This decouples the resets of the CPU usage and
the rate monotonic period statistics.

Update #4528.

4 files changed, 49 insertions, 17 deletions

diff --git a/cpukit/include/rtems/rtems/ratemonimpl.h b/cpukit/include/rtems/rtems/ratemonimpl.h
index 7e42a0437c..62327c5b09 100644
--- a/cpukit/include/rtems/rtems/ratemonimpl.h
+++ b/cpukit/include/rtems/rtems/ratemonimpl.h
@@ -92,7 +92,7 @@ RTEMS_INLINE_ROUTINE Rate_monotonic_Control *_Rate_monotonic_Get(
 void _Rate_monotonic_Timeout( Watchdog_Control *watchdog );
 
 /**
- * @brief _Rate_monotonic_Get_status(
+ * @brief Gets the rate monotonic CPU usage status.
  *
  * This routine is invoked to compute the elapsed wall time and cpu
  * time for a period.
@@ -102,11 +102,8 @@ void _Rate_monotonic_Timeout( Watchdog_Control *watchdog );
  *             since the period was initiated.
  * @param[out] cpu_since_last_period is set to the cpu time used by the
  *             owning thread since the period was initiated.
- *
- * @retval This routine returns true if the status can be determined
- *         and false otherwise.
  */
-bool _Rate_monotonic_Get_status(
+void _Rate_monotonic_Get_status(
   const Rate_monotonic_Control *the_period,
   Timestamp_Control            *wall_since_last_period,
   Timestamp_Control            *cpu_since_last_period
diff --git a/cpukit/include/rtems/score/schedulerimpl.h b/cpukit/include/rtems/score/schedulerimpl.h
index 98f8e337fd..50110ea6e7 100644
--- a/cpukit/include/rtems/score/schedulerimpl.h
+++ b/cpukit/include/rtems/score/schedulerimpl.h
@@ -1270,8 +1270,8 @@ RTEMS_INLINE_ROUTINE void _Scheduler_Update_heir(
   if ( heir != new_heir && ( heir->is_preemptible || force_dispatch ) ) {
 #if defined(RTEMS_SMP)
     /*
-     * We need this state only for _Thread_Get_CPU_time_used().  Cannot use
-     * _Scheduler_Thread_change_state() since THREAD_SCHEDULER_BLOCKED to
+     * We need this state only for _Thread_Get_CPU_time_used_locked().  Cannot
+     * use _Scheduler_Thread_change_state() since THREAD_SCHEDULER_BLOCKED to
      * THREAD_SCHEDULER_BLOCKED state changes are illegal for the real SMP
      * schedulers.
      */
diff --git a/cpukit/include/rtems/score/thread.h b/cpukit/include/rtems/score/thread.h
index e23261701a..aff2f58d77 100644
--- a/cpukit/include/rtems/score/thread.h
+++ b/cpukit/include/rtems/score/thread.h
@@ -853,10 +853,19 @@ struct _Thread_Control {
   Thread_CPU_budget_algorithms          budget_algorithm;
   /** This field is the method invoked with the budgeted time is consumed. */
   Thread_CPU_budget_algorithm_callout   budget_callout;
-  /** This field is the amount of CPU time consumed by this thread
-   *  since it was created.
+
+  /**
+   * @brief This member contains the amount of CPU time consumed by this thread
+   *   since it was created.
+   */
+  Timestamp_Control cpu_time_used;
+
+  /**
+   * @brief This member contains the amount of CPU time consumed by this thread
+   *   at the time of the last reset of the CPU usage by
+   *   rtems_cpu_usage_reset().
    */
-  Timestamp_Control                     cpu_time_used;
+  Timestamp_Control cpu_time_used_at_last_reset;
 
   /** This field contains information about the starting state of
    *  this thread.
diff --git a/cpukit/include/rtems/score/threadimpl.h b/cpukit/include/rtems/score/threadimpl.h
index ace42d8023..a983975568 100644
--- a/cpukit/include/rtems/score/threadimpl.h
+++ b/cpukit/include/rtems/score/threadimpl.h
@@ -1242,15 +1242,41 @@ RTEMS_INLINE_ROUTINE void _Thread_Dispatch_update_heir(
 #endif
 
 /**
- * @brief Gets the used cpu time of the thread and stores it in the given
- *      Timestamp_Control.
+ * @brief Gets the used processor time of the thread throughout its entire
+ *   lifetime.
  *
- * @param the_thread The thread to get the used cpu time of.
- * @param[out] cpu_time_used Stores the used cpu time of @a the_thread.
+ * @param[in, out] the_thread is the thread.
+ *
+ * @return Returns the used processor time of the thread throughout its entire
+ *   lifetime.
  */
-void _Thread_Get_CPU_time_used(
-  Thread_Control    *the_thread,
-  Timestamp_Control *cpu_time_used
+Timestamp_Control _Thread_Get_CPU_time_used( Thread_Control *the_thread );
+
+/**
+ * @brief Gets the used processor time of the thread throughout its entire
+ *   lifetime if the caller already acquired the thread state and home
+ *   scheduler locks.
+ *
+ * @param[in, out] the_thread is the thread.
+ *
+ * @return Returns the used processor time of the thread throughout its entire
+ *   lifetime.
+ */
+Timestamp_Control _Thread_Get_CPU_time_used_locked(
+  Thread_Control *the_thread
+);
+
+/**
+ * @brief Gets the used processor time of the thread after the last CPU usage
+ *   reset.
+ *
+ * @param[in, out] the_thread is the thread.
+ *
+ * @return Returns the used processor time of the thread after the last CPU usage
+ *   reset.
+ */
+Timestamp_Control _Thread_Get_CPU_time_used_after_last_reset(
+  Thread_Control *the_thread
 );
 
 /**